ES2886928T3 - Process for the production of an impact-modified thermoplastic molding composition with improved processing and impact resistance - Google Patents

Abstract

A process for the preparation of a thermoplastic molding composition comprising: A: from 5 to 95% by weight, based on the total molding composition, of at least one thermoplastic copolymer A, comprising at least one vinylaromatic monomer A1 and optionally at least one additional ethylenically unsaturated monomer A2; B: 5 to 70% by weight, based on the total molding composition, of at least one graft copolymer B comprising: B1: 50 to 90% by weight, based on graft copolymer B, of at least a graft base B1 obtained by emulsion polymerization of: B11: 70 to 99.9% by weight, based on the graft base B1, of at least one C1-C8 alkyl (meth)acrylate as monomer B11; B12: 0.1 to 10% by weight, based on the graft base B1, of at least the polyfunctional crosslinking monomer B12; B13: 0 to 29.9% by weight, based on the graft base B1, of at least one additional monoethylenically unsaturated copolymerizable monomer B13 different from B11 and B12; wherein the sum of B11, B12 and optional B13 is 100% by weight; and B2: 10 to 50% by weight, based on graft copolymer B, of at least one graft shell B2, which is obtained by emulsion polymerization in the presence of at least one graft base B1 of: B21: of 50 to 100% by weight, based on graft shell B2, of at least one vinylaromatic monomer B21, and B22: 0 to 50% by weight, based on graft shell B2, of at least one ethylenically unsaturated monomer B22; wherein the total sum of the graft base B1 and the graft cover B2 is 100% by weight; C: 0 to 90% by weight, based on the total molding composition, of at least one additional polymeric component C; and K: from 0 to 40% by weight, based on the total molding composition, of at least one additional additive K; wherein the process encompasses the steps of: a) preparation of the at least one grafting base B1 by emulsion polymerization of monomers B11, B12 and optional B13, where at least one surfactant S1 is added; b) preparation of the at least one graft copolymer B by emulsion polymerization of the at least one optional monomer B21 and B22 in the presence of the at least one graft base B1, wherein at least one surfactant S2 is added before, during and/or or after emulsion polymerization, wherein the graft copolymer B is obtained in the form of a latex with an average particle diameter Dw in the range of 60 to 800 nm; and wherein the volume concentration of the total amount of surfactant S2 is in the range of 0.5 to 0.75 mol/m3, based on the volume of the graft copolymer latex particles B; c) precipitation of the graft copolymer B by mixing the graft copolymer latex obtained in step b) with a precipitation solution comprising at least one salt and/or acid; d) mechanical dehydration, optional washing and/or optional drying of the precipitated graft copolymer B obtained in step c); e) mixing the precipitated graft copolymer B obtained in step d) with component A and optionally components C and/or K, obtaining the thermoplastic molding composition.

Description

DESCRIPTION

Process for the production of an impact-modified thermoplastic molding composition with improved processing and impact resistance

The present invention relates to a process for producing a thermoplastic molding composition comprising a thermoplastic copolymer A, a graft copolymer B and optionally an additional polymeric component C as well as other optional additional additives K, wherein the preparation of the graft copolymer B is carried out by emulsion polymerization, and wherein at least one surfactant S2 is used in the emulsion polymerization grafting step at a volume concentration in the range of 0.5 to 0.75 mol/m3, based on in the volume of the obtained graft copolymer latex particles B; and wherein the average particle diameter Dw of the graft copolymer latex particles B is in the range of 60 to 800 nm. The mechanism of emulsion polymerization for the production of polymer dispersions, referred to as emulsion rubbers or polymer latexes, is well known in the art. Polymeric latexes that are obtained by emulsion polymerization are used for a wide variety of applications, such as emulsion paints, paper coatings, leather finishes, textile finishes, and raw materials for adhesives. Additionally, the use of rubber components prepared by emulsion polymerization for the preparation of impact-modified thermoplastic resins is known.

In particular, rubber components obtained by graft emulsion polymerization having a graft base and a graft shell are used in impact-modified thermoplastic resins. Typically, solid graft copolymers, which can be isolated from the aqueous phase after graft emulsion polymerization, are incorporated into thermoplastic molding compositions to improve the impact strength of the thermoplastic resin. For example, the incorporation of graft copolymer rubbers, e.g. eg grafted crosslinked poly(alkyl(meth)acrylate) rubbers or grafted polybutadiene rubbers, on styrene (co)polymers, such as styrene-acrylonitrile copolymers (SAN) or (alpha)-methylstyrene-acrylonitrile copolymers (AMSAN) to improve the impact resistance of the respective thermoplastic polymer. Such acrylonitrile-butadiene-styrene copolymers (ABS) and acrylonitrile-styrene-acrylate copolymers (ASA) have been used for many years for the production of various moulds, which can be used in many applications, e.g. eg for the automotive or electronic sector. Generally, these impact-modified molds can be produced by polymerizing styrene and acrylonitrile (SAN matrix) in the presence of the graft latex or by blending (eg, by extrusion) the graft copolymer, which is prepared in the form of latex and is insulated separately, and the thermoplastic matrix of SAN.

The synthesis of styrene-acrylonitrile copolymers is known in the art and is, for example, described in US 8,440,764 or by Kunststoff-Handbuch (Vieweg-Daumiller, 15 volume V Polystyrol, Carl-Hanser-Verlag, München, 1969, page 124). The production of graft copolymers comprising at least one rubber is, described, e.g. in EP-A 0450485, DE 195034545 and DE 3149358. For example, the production of thermoplastic resins comprising at least acrylate-based rubber is described in US 2011/0275763. Acrylonitrile styrene acrylate (ASA) copolymer materials are described, for example, in WO 2007/142473 and EP-B 0006503.

Generally, emulsion polymerization starts from an aqueous emulsion of one or more monomers in water, where the emulsion typically comprises one or more surfactants. Polymerization of the monomer is typically initiated by a water-soluble radical initiator. Generally, polymerization takes place in the monomer droplets or micelles, as well as in the latex polymer particles formed during the first few minutes of polymerization. Typically, the latex particles are dispersed in the aqueous medium and are surrounded by the surfactant, thereby reducing coagulation of the latex particles. Small rubber particles, having a defined particle size typically well below 1 pm, can usually be produced to the desired size by adjusting the concentration of surfactant. Typically, the concentration of surfactant in the emulsion polymerization is above the critical micelle concentration (CMC) of the particular surfactant. Graft emulsion polymerization is often carried out by preparing one or more polymer latexes as a graft base in a first step and grafting one or more graft shells onto the graft base by emulsion polymerization of other monomers in the presence of the graft base in a second stage. During the grafting step, additional surfactant is often added to stabilize the emulsion during further growth of the particles.

The formation of coagulated latex particles, particularly during the grafting stage of graft emulsion polymerization, is a serious problem, as coagulated latex particles (clots) result in product loss and reduce product quality. the latexes produced and the products processed later. It is known from the prior art to filter polymer latex to remove the coagulum. Filtration is described, for example, by Houben Weyl XIV/1, in Makromolekulare Stoffe 1, pages 348 to 356 (Georg Thieme Verlag, Stuttgart, 1961) and also in DE-A-4 126 483 and US 4747959 EP-B 1133529 describes styrene copolymers comprising less than 100 ppm of coarse particles, having an average diameter of 200 to 500 pm, with impact strength, thermal stability, color and elongation at break. improved. According to said document, coarse particles are removed by filtration. However, the additional step of the filtration process results in loss of product and a more complex and expensive process.

WO 2017/055179 A1 (D1) describes a process for producing a thermoplastic molding composition based on acrylate graft copolymers, where a sodium carbonate buffer is used in an amount of 0.01 to 4 times the amount molar of sodium carbonate, with respect to the molar amount of initiator. Preferably, the polymerization reaction is carried out in the presence of 0.1% to 1% by weight of an emulsifier, relative to the amount of monomers used. The volume concentration of the surfactant is not mentioned in D1.

Therefore, there is a need for improved and easy graft copolymer preparation processes, where the formation of coagulated latex particles (clots) during emulsion polymerization is avoided or at least reduced.

Surprisingly, it has been found that the amount of coagulum formed during the emulsion polymerization of a latex (hereinafter also referred to as rubbers) is reduced when the concentration of the surfactant used in the grafting step of the emulsion polymerization is controlled as a function of the volume concentration (surfactant concentration based on the volume of the latex particles). In particular, it has been found that the amount of coagulated product is minimized by using a surfactant volume concentration of greater than 0.47 mol/m3 and less than 0.76 mol/m3, where the average particle diameter Dw of the particles latex is preferably in the range of 60 to 800 nm. Furthermore, it has been found that the physical and mechanical properties of thermoplastic molding compositions comprising said optimized latex are improved.

The present invention is directed to a process for the preparation of a thermoplastic molding composition comprising:

A: 5 to 95% by weight, preferably 40 to 90% by weight, more preferably 50 to 90% by weight, based on the total molding composition, of at least thermoplastic copolymer A, comprising at least one vinylaromatic monomer A1 and optionally at least one additional ethylenically unsaturated monomer A2;

B: 5 to 70% by weight, preferably 10 to 60% by weight, more preferably 10 to 50% by weight, based on the total molding composition, of at least one graft copolymer B comprising:

B1: 50 to 90% by weight, preferably 55 to 90% by weight, more preferably 55 to 65% by weight, based on graft copolymer B, of at least one graft base B1 obtained by emulsion polymerization from:

B11: 70 to 99.9% by weight, preferably 87 to 99.5% by weight, based on the graft base B1, of at least one C1-C8 alkyl (meth)acrylate, preferably at least one ( C4-C8 alkyl meth)acrylate, more preferably n-butyl acrylate and/or 2-ethylhexyl acrylate, also preferably only n-butyl acrylate, as monomer B11;

B12: 0.1 to 10% by weight, preferably 0.5 to 5% by weight, also preferably 0.5 to 3% by weight, more preferably 1 to 2.5% by weight, based on the base of graft B1, of at least polyfunctional crosslinking. monomer B12; preferably selected from allyl (meth)acrylate, divinylbenzene, diallyl maleate, diallyl fumarate, diallyl phthalate, triallyl cyanurate, triallyl isocyanurate and dihydrodicyclopentadienyl acrylate (DCPA), more preferably allyl (meth)acrylate and/or dihydrodicyclopentadienyl acrylate;

B13: 0 to 29.9 wt%, preferably 0 to 20 wt%, more preferably 0 to 10 wt%, also preferably 0.5 to 10 wt%, based on graft base B1 , of at least one additional monoethylenically unsaturated copolymerizable monomer B13 other than B11 and B12, preferably selected from styrene, a(alpha)-methylstyrene, (C1-C4)alkylstyrene, acrylonitrile, methacrylonitrile, isoprene, butadiene, chloroprene, (meth) methyl acrylate, alkylene glycol di(meth)acrylate and vinyl methyl ether,

wherein the sum of B11, B12 and optional B13 is 100% by weight (based on all monomers of graft base B1); Y

B2: 10 to 50 wt%, also preferably 10 to 45 wt%, more preferably 35 to 45 wt%, based on graft copolymer B, of at least one graft shell B2, which is obtained by emulsion polymerization in the presence of at least one graft base B1 of:

B21: 50 to 100% by weight, preferably 50 to 95% by weight, more preferably 65 to 80% by weight, also preferably 75 to 80% by weight, based on graft cover B2, of at least a vinylaromatic monomer B21, preferably selected from styrene, a(alpha)-methylstyrene or mixtures of styrene and at least one additional monomer selected from a(alpha)-methylstyrene, p(para)methylstyrene and C-pC8 alkyl (meth)acrylate (preferably C-pC4 alkyl (meth)acrylate, e.g. methacrylate methyl or ethyl methacrylate), and

B22: 0 to 50 wt%, preferably 5 to 50 wt%, more preferably 20 to 35 wt%, also preferably 20 to 25 wt%, based on graft cover B2, of at least an ethylenically unsaturated monomer B22, preferably selected from acrylonitrile or mixtures of acrylonitrile and at least one additional monomer selected from methacrylonitrile, acrylamide, vinyl methyl ether, unsaturated carboxylic acid anhydrides (eg maleic anhydride or italic acid anhydride) and imides of unsaturated carboxylic acids (eg, N-substituted maleimides, such as N-cyclohexylmaleimide or N-phenylmaleimide);

wherein the total sum of the graft base B1 and the graft cover B2 is 100% by weight;

C: 0 to 90% by weight, preferably 0 to 50% by weight, more preferably 5 to 20% by weight, based on the total molding composition, of at least one additional polymeric component C; and K: 0 to 40% by weight, preferably 0 to 10% by weight, more preferably 0.1 to 5% by weight, based on the total molding composition, of at least one additional additive K;

where the procedure includes the stages of:

a) preparation of the at least one grafting base B1 by emulsion polymerization of the optional monomers B11, B12 and B13, where at least one surfactant S1 is added;

b) preparation of the at least one graft copolymer B by emulsion polymerization of the at least one optional monomer B21 and B22 in the presence of at least one graft base B1, wherein at least one surfactant S2 is added before, during and/or after emulsion polymerization, wherein the graft copolymer B is obtained in the form of a latex with an average particle diameter Dw in the range of 60 to 800 nm; and J wherein the volume concentration of the total amount of surfactant S2 is in the range of 0.5 to 0.75 mol/m, based on the volume of the graft copolymer latex particles B;

c) precipitation of the graft copolymer B by mixing the graft copolymer latex obtained in step b) with a precipitation solution comprising at least one salt and/or acid;

d) mechanical dehydration, optional washing and/or optional drying of the precipitated graft copolymer B obtained in step c);

e) mixing the precipitated graft copolymer B obtained in step d) with component A and optionally components C and/or K, obtaining the thermoplastic molding composition.

In a preferred embodiment, the amounts of components A and B add up to 100% by weight. In another preferred embodiment, the amounts of components A and B and optional components C and/or K add up to 100% by weight. In particular, the minimum and/or maximum amount of thermoplastic copolymer A can be adapted so that the sum of the compounds results in 100% by weight.

In terms of the present invention, the term alkyl (meth)acrylate, e.g. eg Methyl (meth)acrylate encompasses the respective alkyl acrylates, alkyl methacrylates and mixtures thereof, e.g. eg methyl acrylate, methyl methacrylate and mixtures thereof.

thermoplastic copolymer A

Preferably, the thermoplastic copolymer A comprising at least one vinylaromatic monomer is a resin that is free of any latex-type polymer (non-rubber resin).

Preferably, the thermoplastic copolymer A comprises at least 50% by weight of one or more vinylaromatic monomers A1, preferably selected from styrene, a(alpha)-methylstyrene, p(para)methylstyrene and optionally at least one additional ethylenically unsaturated monomer A2. Additionally, a thermoplastic copolymer A is prepared from blends of styrene with other comonomers A2. In particular, the at least one thermoplastic copolymer A can be selected from polystyrene, copolymers of styrene, e.g. eg copolymers of styrene and acrylonitrile (SAN), copolymers of a(alpha)-methylstyrene, e.g. eg a(alpha)-methylstyrene and acrylonitrile copolymers (AMSAN). In general, any SAN and/or AMSAN copolymer known in the art can be used as thermoplastic copolymer A within the scope of the present invention.

In particular, thermoplastic copolymer A is selected from SAN and/or AMSAN copolymers comprising less than 36% by weight of acrylonitrile as monomer A2, based on copolymer A. Preferably, thermoplastic copolymer A comprises at least one vinylaromatic monomer A1, preferably styrene, in an amount of 50 to 99% by weight, preferably 60 to 95% by weight, also preferably 65 to 90% by weight. weight, more preferably 65 to 70% by weight, and at least one vinyl cyanide monomer A2, preferably acrylonitrile, in an amount of 1 to 50% by weight, preferably 5 to 40% by weight, also preferably 10 to 35% by weight, more preferably from 30 to 35% by weight.

In a preferred embodiment, the at least one thermoplastic copolymer A comprises (preferably consists of):

A1: 50 to 99% by weight, preferably 50 to 95% by weight, more preferably 60 to 90% by weight, also preferably 60 to 85% by weight, based on copolymer A, of the at least one monomer vinylaromatic A1, selected from styrene, a(alpha)-methylstyrene or mixtures of styrene and at least one additional monomer selected from a(alpha)-methylstyrene, p(para)methylstyrene and C1-C8 alkyl (meth)acrylate,

A2: 1 to 50% by weight, 50 to 99% by weight, preferably 5 to 50% by weight, more preferably 10 to 40% by weight, also preferably 15 to 40% by weight, based on the copolymer A, of at least one additional ethylenically unsaturated monomer A2, selected from acrylonitrile or mixtures of acrylonitrile and at least one additional monomer selected from methacrylonitrile, acrylamide, vinyl methyl ether, unsaturated carboxylic acid anhydrides and unsaturated carboxylic acid imides.

In particular, a thermoplastic copolymer A comprising 35% by weight or less of acrylonitrile, based on the total copolymer A, is preferred.

In a preferred embodiment of the invention, the at least one vinylaromatic monomer A1 is styrene or alphamethylstyrene, and the at least one additional ethylenically unsaturated monomer A2 is acrylonitrile. In a further preferred embodiment of the invention, monomer A1 is a mixture of styrene and a (alpha)-methylstyrene and monomer A2 is acrylonitrile, wherein the mixture preferably comprises at least 10% by weight, preferably at least 50% by weight and more preferably at least 90% by weight, based on the total amount of monomer A1, styrene.

In a preferred embodiment, the thermoplastic copolymer A is composed of the monomers A1 and A2, where the at least one vinylaromatic monomer A1 is selected from styrene, a(alpha)-methylstyrene and mixtures thereof; and the at least one additional ethylenically unsaturated monomer A2 is acrylonitrile or a mixture of acrylonitrile and methacrylonitrile.

Especially preferred are thermoplastic copolymers A comprising (preferably consisting of):

A1: 60 to 95% by weight, preferably 60 to 90% by weight, more preferably 60 to 85% by weight, also preferably 65 to 80% by weight, based on the total copolymer A, of at least one vinylaromatic monomer A1, selected from styrene, a(alpha)-methylstyrene or mixtures of styrene and a(alpha)-methylstyrene; Y

A2: 5 to 40% by weight, preferably 10 to 50% by weight, more preferably 15 to 40% by weight, also preferably 20 to 35% by weight, based on the total copolymer A, of at least one additional ethylenically unsaturated monomer A2, selected from acrylonitrile or mixtures of acrylonitrile and methacrylonitrile.

In particular, the weight average molecular weight (Mw) of the thermoplastic copolymer A is in the range of 15,000 to 200,000 g/mol, preferably in the range of 30,000 to 150,000 g/mol. Generally, the number average molar mass (Mn) of the thermoplastic copolymer A amounts to 15,000 to 100,000 g/mol. Preferably, the average molecular weight can be determined by gel permeation chromatography (GPC) relative to polystyrene as standard and using, for example, UV detection. Preferably, the thermoplastic copolymer A has a viscosity index VN (determined according to DIN 53726 at 25°C, 0.5% by weight in dimethylformamide) of 50 to 120 ml/g, preferably 50 to 100 ml/g, more preferably from 55 to 85 ml/g.

In a preferred embodiment, the thermoplastic copolymer A is a SAN (styrene and acrylonitrile copolymer) or AMSAN (alpha-methylstyrene and acrylonitrile copolymer) copolymer, which has an average molecular weight and/or viscosity in the aforementioned ranges.

Copolymer A can be prepared by all known methods, eg bulk polymerization, solution polymerization, suspension polymerization and emulsion polymerization or mixed process, e.g. g., bulk/suspension polymerizations, with or without other components. The synthesis of thermoplastic copolymers A is possible by thermal initiation or by the addition of initiators, especially radical initiators, such as peroxides. Suitable thermoplastic copolymers A are preferably produced by bulk or solution polymerization.

More preferably, thermoplastic copolymer A is prepared from the components acrylonitrile and styrene and/or α-methylstyrene by bulk polymerization or in the presence of one or more solvents, for example, toluene or ethylbenzene. A polymerization procedure is described, for example, by Kunststoff-Handbuch [Plastics Handbook], Vieweg-Daumiller, volume V, (Polystyrol) [Polystyrene], Carl-Hanser-Verlag, Munich 1969, pages 122 And next.

Details are described, for example, in US 4,009,226 and US 4,181,788 relating to the production of SAN and/or AMSAN resins by bulk polymerization or solution polymerization. Additionally, the synthesis of thermoplastic copolymer A is described, for example, in DE-A 2420358 and DE-A 27 24360. Suitable thermoplastic copolymers are also described in De-A 19713509.

Graft Copolymer B

Often the graft copolymer B has a complex structure and is essentially composed of one or more graft bases B1 and one or more graft caps B2. Typically, the graft copolymer B is produced in the form of a latex (rubber) by emulsion polymerization in steps a) and b), where one or more graft bases B1 are first obtained by emulsion polymerization of the monomers B11 , B12 and optionally B13 as described and thereafter one or more graft shells B2 are obtained by graft emulsion polymerization of monomers B21 and B22 as described in the presence of one or more of the graft base B1. Preferably, the graft copolymer latex B is polymerized by free radical aqueous emulsion polymerization. The reaction is typically initiated by water-soluble or oil-soluble free radical polymerization initiators, e.g. eg inorganic or organic peroxides, such as peroxodisulfate or benzoyl peroxide, or with the aid of redox initiator systems. WO 2002/10222, DE-A 28 26 925, and also EP-A 022200 describe suitable polymerization processes.

The at least one graft copolymer B is present in the thermoplastic molding composition in an amount of at least 5% by weight, preferably at least 10% by weight, more preferably at least 15% by weight, based on the molding composition. full thermoplastic.

Preferably, the graft copolymer B is selected from acrylonitrile styrene acrylate (ASA) graft copolymers comprising a crosslinked poly(alkyl(meth)acrylate) rubber as graft base B1, in particular a poly (butyl acrylate) crosslinked B1.

Typically, the graft base B1 consists of a polymer, preferably an at least partially crosslinked polymer, with a glass transition temperature below 0°C, preferably below -20°C, more preferably below -40°C. C, where the glass transition temperature Tg is measured by dynamic mechanical analysis (DMA) using a frequency of 1 Hz.

The at least one graft shell B2 typically consists of monomers that copolymerize to produce a polymer with a glass transition temperature of 20°C or more, preferably more than 60°C. The preferred monomers of the graft cover B2 (monomers B21 and B22) are selected from styrene, a(alpha)-methylstyrene, (meth)acrylonitrile, methyl (meth)acrylate, ethyl acrylate, N-phenylmaleic imide and maleic anhydride. .

Preferred monomers B11 for producing the graft base B1 are alkyl acrylates and/or alkyl methacrylates (also called alkyl (meth)acrylates) with 1 to 8, preferably 4 to 8, carbon atoms being present in the alkyl group. . Preferably, monomer B11 is selected from C4-C8 alkyl acrylates, preferably selected from butyl acrylate, ethylhexyl acrylate and cyclohexyl acrylate. n-Butyl acrylate and/or 2-ethylhexyl acrylate are particularly preferred, n-butyl acrylate alone or mixed with other monomers B11, such as monomer B11, is more preferred.

In order to have crosslinking of the C1-C8 alkyl (meth)acrylate monomers B11 and thus crosslinking of the grafting base B1, the monomers B11 are polymerized in the presence of 0.1 to 10% by weight, preferably of 0.1 to 5% by weight, preferably 0.5 to 3% by weight, preferably 1 to 4% by weight, more preferably 1 to 2.5% by weight, based on graft base B1, of one or more polyfunctional crosslinking monomers B12. Suitable monomers B12 are especially polyfunctional crosslinking monomers which can be copolymerized with the monomers mentioned, especially B11 and B13. Suitable polyfunctional crosslinking monomers B12 comprise two or more, preferably two or three, more preferably exactly two ethylenic double bonds, preferably non-1,3-conjugated. Examples of suitable polyfunctional crosslinking monomers B12 are allyl (meth)acrylate, divinylbenzene, dicarboxylic acid diallyl ester, e.g. eg diallyl maleate, diallyl fumarate and diallyl phthalate. The acrylic acid ester of tricyclodecenyl alcohol (dihydrodicyclopentadienyl acrylate, DCPA), as described in DE-A 1260135, also represents a preferred polyfunctional crosslinking monomer B12.

Especially, the polyfunctional crosslinking monomer B12 (preferably used for crosslinking poly(alkyl(meth)acrylate rubber) is at least one monomer selected from allyl (meth)acrylate, divinylbenzene, diallyl maleate, diallyl fumarate, diallyl phthalate, triallyl cyanurate, triallyl isocyanurate and dihydrodicyclopentadienyl acrylate (DCPA), preferred allyl (meth)acrylate, divinylbenzene, diallyl maleate, diallyl fumarate, diallyl phthalate and dihydrodicyclopentadienyl acrylate (DCPA), preferably among allyl (meth)acrylate and dihydroacrylatepentadienyl.

In a preferred embodiment, 1 to 2.5% by weight is used, preferably 1.5 to 2.1% by weight, based on the graft base B1, of dihydrodicidopentadienyl acrylate (DCPA) alone or in a mixture with at least one of the additional monomers B12 mentioned above, in particular mixed with allyl (meth)acrylate, as monomer B12.

Furthermore, the at least one grafting base B1 may optionally comprise one or more monoethylenically unsaturated copolymerizable monomers B13, different from B11 and B12. The monomers B13 can be selected, for example, from butadiene, isoprene, styrene, acrylonitrile, methyl (meth)acrylate and vinyl methyl ether. Preferably, the additional monomer B13 is at least one monomer selected from styrene, a(alpha)-methylstyrene, acrylonitrile; methacrylonitrile, methyl (meth)acrylate, isoprene, chloroprene and (Ci-C4)alkylstyrene.

In a preferred embodiment, the vinylaromatic monomer B21 (in particular each of monomers B21, B21' and B21") is styrene and/or a(alpha)-methylstyrene and the at least one ethylenically unsaturated monomer B22 (in particular each of monomers B22 and B22") is acrylonitrile or a mixture of acrylonitrile and at least one monomer selected from methacrylonitrile, acrylamide, vinyl methyl ether, maleic acid anhydride, italic acid anhydride, N-cyclohexylmaleimide and N-phenylmaleimide. More preferably, the monomers B21 and B22 used for the emulsion polymerization of graft copolymer B are mixtures of styrene and acrylonitrile having a weight ratio of styrene to acrylonitrile in the range of 95:5 to 50:50, more preferably in the range from 80 : 20 to 65 : 35.

In a preferred embodiment, graft copolymer B comprises (preferably consists of):

B1: 55 to 75% by weight, based on graft copolymer B, of at least one graft base B1 obtained by emulsion polymerization of:

B11: 90 to 99.9% by weight, preferably 95 to 99.5% by weight, also preferably 97 to 99.5% by weight, more preferably 97.5 to 99% by weight, based on the graft base B1, of at least one C1-C8 alkyl (meth)acrylate, preferably at least one C4-C8 alkyl (meth)acrylate, more preferably n-butyl acrylate and/or 2-ethylhexyl acrylate, also preferably only n-butyl acrylate, as monomer B11;

B12: 0.1 to 10% by weight, preferably 0.5 to 5% by weight, also preferably 0.5 to 3% by weight, more preferably 1 to 2.5% by weight, based on the graft base B1, of at least one polyfunctional crosslinking monomer B12; wherein monomer B12 is selected from allyl (meth)acrylate, divinylbenzene, diallyl maleate, diallyl fumarate, diallyl phthalate, triallyl cyanurate, triallyl isocyanurate and dihydrodicyclopentadienyl acrylate (DCPA), more preferably (meth)acrylate allyl and dihydrodicyclopentadienyl acrylate;

B13 optionally up to 9.9 wt%, preferably 0 to 9.9 wt%, more preferably 0 to 4.5 wt%, based on graft base B1, of at least one monoethylenically unsaturated copolymerizable monomer B13 other than B11 and B12, wherein the monomer B13 is selected from styrene, a(alpha)-methylstyrene, (C1-C4)alkylstyrene, acrylonitrile, methacrylonitrile, isoprene, butadiene, chloroprene, methyl (meth)acrylate, di alkylene glycol vinyl methyl ether (meth)acrylate,

wherein the sum of B11, B12 and optional B13 is 100% by weight (based on all monomers of graft base B1); Y

B2: 25 to 45% by weight, based on graft copolymer B, of at least one graft shell B2, preferably one to three graft shells B2, where at least one graft shell B2 is obtained by emulsion polymerization in the presence of at least one graft base B1 of:

B21: 70 to 80% by weight, based on graft cover B2, at least one vinylaromatic monomer B21, wherein monomer B21 is selected from styrene, a(alpha)-methylstyrene and mixtures of styrene and one additional monomer selected from a(alpha)-methylstyrene, p-methylstyrene, C1-C4 alkyl (meth)acrylate (eg, methyl (meth)acrylate, ethyl (meth)acrylate), preferably selected from styrene, a(alpha )-methylstyrene or mixtures of styrene and (alpha)-methylstyrene or methyl (meth)acrylate, and

B22: from 20 to 30% by weight, based on graft cover B2, of at least one ethylenically unsaturated monomer B22, wherein monomer B22 is selected from acrylonitrile or mixtures of acrylonitrile and at least one additional monomer selected from methacrylonitrile, acrylamide, vinyl methyl ether, unsaturated carboxylic acid anhydrides (eg, maleic acid anhydride, italic acid anhydride), and unsaturated carboxylic acid imides (eg, N-substituted maleimide, such as N-cyclohexylmaleimide and N-phenylmalimide ), preferably selected from acrylonitrile or mixtures of acrylonitrile and methacrylonitrile; wherein the total sum of the graft base(s) B1 and the graft cover(s) B2 is 100% by weight.

In a preferred embodiment, the at least one graft base B1 is obtained by emulsion polymerization of: B11: 90 to 99.9 wt%, preferably 97 to 99.5 wt%, more preferably 97.5 to 99 wt%, based on graft base B1, of at least one (met) C1-C8 alkyl acrylate, preferably at least one C4-C8 alkyl (meth)acrylate, more preferably n-butyl acrylate and/or 2-ethylhexyl acrylate, most preferably n-butyl acrylate, as monomer B11; Y

B12: 0.1 to 10% by weight, preferably 0.5 to 3% by weight, more preferably 1 to 2.5% by weight, based on the graft base B1, of at least one crosslinking monomer polyfunctional B12; selected from allyl (meth)acrylate, divinylbenzene, diallyl maleate, diallyl fumarate, diallyl phthalate and dihydrodicyclopentadienyl acrylate (DCPA), especially from allyl (meth)acrylate and/or dihydrodicyclopentadienyl acrylate (DCPA);

wherein the sum of B11 and B12 is 100% by weight (based on all monomers of graft base B1). In particular, further suitable compositions of the grafting base B1, comprising the monomers B11, B12 and optionally B13, as well as the general method for their preparation are described, for example, in DE-A 2826925, DE -A 3149358 and document DE-A 3414118.

In a preferred embodiment, the at least one graft cover B2 is obtained by emulsion polymerization in the presence of the at least one graft base B1 of:

B21: 50 to 95% by weight, preferably 65 to 80% by weight, more preferably 70 to 80% by weight, based on graft cover B2, of at least one vinylaromatic monomer B21, wherein monomer B21 is selected from styrene, a(alpha)-methylstyrene, or mixtures of styrene and an additional monomer selected from a(alpha)-methylstyrene, p(para)methylstyrene, C1-C4 alkyl (meth)acrylate (eg, ( methyl meth)acrylate, ethyl (meth)acrylate), preferably selected from styrene, a(alpha)-methylstyrene or mixtures of styrene and a(alpha)-methylstyrene or methyl (meth)acrylate, and

B22: 5 to 50% by weight, preferably 20 to 35% by weight, more preferably 20 to 30% by weight, based on the graft cover B2, of at least one ethylenically unsaturated monomer B22, wherein the monomer B22 is selected from acrylonitrile or mixtures of acrylonitrile and at least one additional monomer selected from methacrylonitrile, acrylamide, vinyl methyl ether, unsaturated carboxylic acid anhydrides (eg, maleic anhydride, phthalic acid anhydride), and unsaturated carboxylic acid imides (eg, N-substituted maleimide, such as N-cycloimide and N-phenylmalimide), preferably selected from acrylonitrile or mixtures of acrylonitrile and methacrylonitrile.

In particular, graft copolymer B comprises a graft base B1, preferably a crosslinked poly(alkyl(meth)acrylate) rubber described above, and one or more graft shells B2, in particular one, two or three graft shells. graft B2, which differ in the selection and quantity of the monomers B21 and B22 and which are obtained by stepwise graft emulsion polymerization of the monomers B21 and/or B22 in the presence of the graft base B1 res. in the presence of already grafted graft base.

In a preferred embodiment, graft copolymer B comprises at least one graft base B1, preferably a crosslinked poly(butyl acrylate) rubber described above, and exactly one graft shell B2, obtained by emulsion polymerization of monomers B21 and B22 as described above, especially styrene and acrylonitrile, in the presence of graft base B1 (single stage grafting).

In a further preferred embodiment, graft copolymer B comprises at least one graft base B1, preferably a crosslinked poly(butyl acrylate) rubber described above, and two graft shells B2' and B2", where B2' is obtained from the emulsion polymerization of monomer B21, especially styrene, in the presence of graft base B1 and graft shell B2" is obtained from the subsequent emulsion polymerization of monomers B21 and B22 as described above, especially styrene and acrylonitrile, in the presence of grafting base B1 grafted with B2' (two-stage grafting).

In a preferred embodiment (single stage grafting), graft copolymer B comprises:

B1: 50 to 70% by weight, preferably 55 to 65% by weight, more preferably 58 to 65% by weight, based on graft copolymer B, of at least one, preferably exactly one, graft base B1 as described above, wherein preferably the at least one graft base B1 has a mean particle diameter Dw in the range of 60 to 200nm, preferably 60 to 150nm, more preferably 60 to 100nm;

B2: 30 to 50 wt%, preferably 35 to 45 wt%, more preferably 35 to 42 wt%, based on graft copolymer B, of one or more, preferably exactly one graft shell B2, obtained by emulsion polymerization, in the presence of at least one graft base B1, of:

B21: 50 to 95 wt%, preferably 65 to 80 wt%, more preferably 70 to 80 wt%, based on graft base B, of at least one vinylaromatic monomer B21, wherein monomer B21 is selected from styrene, a(alpha)-methylstyrene or mixtures of styrene and at least one monomer selected from a(alpha)-methylstyrene, p-methylstyrene, and C1-C4 alkyl (meth)acrylate (eg, methyl (meth)acrylate, ethyl (methacrylate), preferably selected from styrene, a(alpha )-methylstyrene or mixtures of styrene with a(alpha)-methylstyrene or methyl (meth)acrylate; and

B22: 5 to 50% by weight, preferably 20 to 35% by weight, more preferably 20 to 30% by weight, based on the graft cover B2, of at least one ethylenically unsaturated monomer B22, wherein the monomer B22 is selected from acrylonitrile or mixtures of acrylonitrile and at least one additional monomer selected from methacrylonitrile, acrylamide, vinyl methyl ether, unsaturated carboxylic acid anhydrides (eg, maleic acid anhydride, italic acid anhydride), and unsaturated carboxylic acid imides (eg, N-substituted maleimide, such as N-cyclohexylmaleimide and N-phenylmaleimide), preferably selected from acrylonitrile or mixtures of acrylonitrile and methacrylonitrile;

wherein the total sum of the graft base B1 and the graft cover B2 is 100% by weight.

In another preferred embodiment (two-stage graft B2' and B2") the graft copolymer B comprises:

B1: 50 to 70% by weight, preferably 55 to 65% by weight, more preferably 58 to 65% by weight, based on graft copolymer B, of at least one, preferably exactly one, graft base B1 as described above, wherein preferably the at least one graft base B1 has a mean particle diameter Dw in the range of 200 to 800nm, preferably 300 to 600nm, more preferably 350 to 550nm;

B2': 10 to 30 wt%, preferably 10 to 20 wt%, more preferably 10 to 15 wt%, based on graft copolymer B, of at least one graft shell B2', which is obtained by emulsion polymerization, in the presence of graft base B1, of

B21': 100% by weight, based on the graft cover B2', of at least one vinylaromatic monomer B21', selected from styrene, a(alpha)-methylstyrene or a mixture of styrene and at least one additional monomer selected from a (alpha)-methylstyrene, p-methylstyrene, and C1-C4 alkyl (meth)acrylate (eg, methyl (meth)acrylate, ethyl (meth)acrylate); Y

B2": 20 to 40 wt%, preferably 20 to 30 wt%, more preferably 25 to 30 wt%, based on graft copolymer B, of at least one graft shell B2", which is obtained by emulsion polymerization, in the presence of graft base B1 grafted with B2', of:

B21": 50 to 95% by weight, preferably 65 to 80% by weight, more preferably 70 to 80% by weight, based on graft cover B2", of at least one vinylaromatic monomer B21", selected from styrene, a(alpha)-methylstyrene, or mixtures of styrene and at least one additional monomer selected from alpha-methylstyrene, p-methylstyrene, and C1-C4 alkyl (meth)acrylate (eg, methyl (meth)acrylate, ethyl (meth)acrylate), preferably selected from styrene, a(alpha)-methylstyrene or mixtures of styrene and a(alpha)-methylstyrene or methyl (meth)acrylate; and

B22": 5 to 50% by weight, preferably 20 to 35% by weight, more preferably 20 to 30% by weight, based on graft cover B2", at least one ethylenically unsaturated monomer B22, selected from acrylonitrile or mixtures of acrylonitrile and at least one additional monomer selected from methacrylonitrile, acrylamide, vinyl methyl ether, unsaturated carboxylic acid anhydrides (eg, maleic acid anhydride, italic acid anhydride), and unsaturated carboxylic acid imides (eg, acetylsalicylic acid anhydride). , N-substituted maleimide, such as N-cyclohexylmaleimide and N-phenylmaleimide).

According to a preferred embodiment, graft copolymer B is a blend of the above-described embodiments of one-stage graft copolymer B and two-stage graft copolymer B (including graft B2' and B2”).

More preferably, the monomers B21, B21' and B21'' are styrene or mixtures of styrene and a(alpha)-methylstyrene. More preferably, monomers B22 and B22" are acrylonitrile or mixtures of acrylonitrile and at least one additional monomer selected from methacrylonitrile, maleic acid anhydride, N-cyclohexylmaleimide, N-phenylmaleimide, more preferably acrylonitrile or mixtures of acrylonitrile and at least one monomer selected from methacrylonitrile and maleic acid anhydride In a more preferred embodiment of the invention, monomers B21, B21' and B21" are styrene and monomers B22 and B22' are acrylonitrile.

In a preferred embodiment of the invention, the method of the invention covers the synthesis of at least two, preferably two, three or four different graft copolymers BI and B-II, wherein the graft copolymers BI and B-II differ in its mean particle diameter Dw. In this preferred embodiment, graft copolymer B especially comprises at least two graft copolymers B-I and B-II, preferably based on crosslinked C1-C8 alkyl (meth)acrylate graft bases B1 as described above, wherein:

The BI graft copolymer (small size ASA rubber) has a mean particle diameter Dw in the range of 60 to 200 nm, preferably 80 to 150 nm, more preferably 90 to 100 nm, and

The graft copolymer B-II (large size ASA rubber) has an average particle diameter Dw in the range of 300 to 800 nm, preferably 300 to 700 nm, more preferably 400 to 600 nm.

The graft copolymer BI (small size ASA rubber) is preferably obtained by emulsion polymerization of monomers B21 and B22 as described above, in particular styrene or a(alpha)-methylstyrene as B21 and acrylonitrile as B22, in the presence of the previously prepared graft base B1 (B1-I) as described above.

Preferably, graft copolymer B-II (oversized ASA rubber) is desired to have a narrow particle size distribution, wherein the particle size distribution Q = (Dg0-D-i0)/D50 is less than 0.3, preferably less than 0.2.

Suitable graft bases B1 of the crosslinked Ci-Ca alkyl (meth)acrylate polymer of graft copolymer B-II (referred to as B1-II) can be produced according to known procedures for the production of large-size dispersions, conveniently by seed polymerization, as described in DE 1911 882 for the production of ASA polymers. According to this method, a small-sized crosslinked acrylate latex (seed latex) having an average particle diameter Dw of 50 to 180 nm, preferably less than 120 nm, which is obtained from the emulsion polymerization of ( C1-C8 alkyl meth)acrylates as monomers B11, crosslinking monomers B12 and optionally other comonomers B13, are subjected to a further polymerization reaction. In particular, the reaction conditions are adjusted such that they only allow further growth of the present seed latex particles, without forming new latex particles (described in Journal of Applied Polymer Science, vol. 91965, p. 2929 a 2938). An initiator is typically used in such a method. The particle size of the resulting graft copolymer B-II (oversized rubber) can be adjusted by varying the ratio of seed latex to monomers. The graft copolymer B-II is preferably obtained by emulsion polymerization of the monomers B21 and B22 as described above, in particular styrene or a(alpha)-methylstyrene as B21 and acrylonitrile as B22, in the presence of the graft base B1- II previously prepared.

The thermoplastic molding composition according to the invention can be prepared, for example, by mixing the graft copolymers B-I and B-II, especially the graft copolymers B-I and B-II, are mixed in step e) (mixing of the components). Preferably, the graft copolymers B-I and B-II described above are prepared, precipitated and dehydrated separately in steps a) to d). It is also possible to mix latex graft copolymers B-I and B-II after producing them separately in steps a) and b) and precipitating them together in step c). The following steps, such as dehydration in step d) and mixing with other components in step e), can be carried out as described.

The weight ratio of the graft copolymers B-I and B-II can be varied within wide ranges. Preferably, graft copolymer B is a blend of graft copolymer BI and B-II, wherein the weight ratio of BI: B-II is from 90:10 to 10:90, preferably from 80:20 to 20: 80 and more preferably from 70:30 to 35:65.

It is also possible to obtain graft copolymers with different particle sizes, especially bimodal particle size distributions of 60 to 200 nm and 300 to 800 nm, by known agglomeration methods. Graft copolymers with large and small particle sizes are described, for example, in DE-A 3615607.

Furthermore, graft copolymers B having two or more different graft shells B2 can be used as described above. Additionally, graft copolymers with multilayer graft shells are described, for example, in EP-A 0111260 and WO 2015/078751.

Additional Polymer Component C

Optionally, the thermoplastic molding composition comprises 0 to 90% by weight, preferably 0 to 60% by weight, also preferably 0.5 to 30% by weight, more preferably 30 to 90% by weight, based on the total molding composition, of at least one additional polymeric component C. Preferably, the optional polymeric component C is selected from polycarbonates (including aromatic polycarbonates and aromatic polyestercarbonates), polyamides and polyesters, more preferably from polycarbonates and polyamides.

In a preferred embodiment, the thermoplastic molding composition comprises from 5 to 60% by weight, preferably from 20 to 60% by weight, more preferably from 30 to 60% by weight, based on the total molding composition, of at least one additional polymeric component P selected from polycarbonates, polyamides and polyesters.

Preferably, the at least one additional polymeric component C is at least one aromatic polycarbonate and/or at least one aromatic polyestercarbonate. Suitable aromatic polycarbonates and/or aromatic polyestercarbonates are described in the prior art and can be prepared by known methods. For example, the preparation of aromatic polycarbonates is described by Schnell, in "Chemistry and Physics of Polycarbonates", Interscience Publishers, 1964 and in ^E-AS 1495626, DE-A 2232877, DE-A 2703 376, DE-A 2714544, DE-A 3000610 and DE-A 3832396. In particular, the preparation of aromatic polycarbonate and/or aromatic polyestercarbonate is carried out by reacting diphenols, preferably bisphenol A, carbonic acid halides, preferably phosgene and optionally aromatic dicarboxylic acid halides, preferably benzenedicarboxylic acid halides. In particular, suitable aromatic polycarbonates and aromatic polyestercarbonates and their preparation are described in DE-A 2714544, DE-A 3 000610, and DE-A 3832396.

The aromatic polycarbonates and/or aromatic polyestercarbonates used as component C can be linear or branched in a known manner. Branching agents that can be used are carboxylic acid chlorides that are trifunctional or more than trifunctional, eg described in DE-A 2940024, or phenols that are trifunctional or more than trifunctional.

Typically, aromatic polycarbonates and polyestercarbonates suitable as component C have weight average molecular weights (Mw, measured eg by ultracentrifuge or scattered light measurement) of 10,000 to 200,000 g/mol, preferably 15,000 to 80,000 g/mol, particularly preferably from 24,000 to 32,000 g/mol.

The relative solution viscosity (qrel) of the aromatic polycarbonates and polyester carbonates used as component C is typically in the range of 1.18 to 1.4, preferably 1.20 to 1.32 (measured in 0.5 g of polycarbonate or polyester carbonate in 100 ml of methylene chloride solution at 25°C). The thermoplastic aromatic polycarbonates and polyestercarbonates may be employed by themselves or in any desired mixture of one or more, preferably one to three or one or two thereof. More preferably, only one type of polycarbonate is used.

Preferably, the aromatic polycarbonate used as component C is a polycarbonate based on bisphenol A and phosgene, including polycarbonates that have been prepared from the corresponding precursors or synthetic building blocks of bisphenol A and phosgene.

Also preferably, the at least one additional polymeric component C can be at least one polyamide selected from homopolyamides, copolyamides and mixtures of such polyamides. Suitable polyamides and methods for their production are known from the state of the art. In particular, suitable semi-crystalline polyamides are polyamide-6, polyamide-6,6, mixtures and corresponding copolymers of these components. Also included are polyamides in which the acid component consists wholly or partially of terephthalic acid, isophthalic acid, suberic acid, sebacic acid, azelaic acid, adipic acid and/or cyclohexanedicarboxylic acid, the diamine component wholly or partially consists of m- and/or p-xylylenediamine, hexamethylenediamine, 2,2,4-trimethylhexamethylenediamine, 2,2,4-trimethylhexamethylenediamine and/or isophorone diamine. In particular, as additional component C, amorphous polyamides can be used which are obtained by polycondensation of diamines, such as ethylenediamine, hexamethylenediamine, decamethylenediamine, 2,2,4- and/or 2,4,4-trimethylhexamethylenediamine, m- and/or Pxylenediamine, Bis-(4-Aminocyclohexyl)-Methane, Bis-(4-Aminocyclohexyl)Propane, 3,3'-Dimethyl-4,4'-Diaminodicyclohexylmethane, 3-Aminomethyl-3,5,5-Trimethyl-Cyclohexylamine, 2 ,5- and/or 2,6-bis-(aminomethyl)-norbornane and/or 1,4-diamino-methylcyclohexane, with dicarboxylic acids such as oxalic acid, adipic acid, azelaic acid, azelaic acid, decanedicarboxylic acid, heptadecanedicarboxylic acid , 2,2,4- and/or 2,4,4-trimethyladipic acid, isophthalic acid and terephthalic acid.

Preferably, the polyamides suitable as component C have a relative viscosity (measured in a 1% by weight solution in m-cresol or in a 1% (w/v) solution in 96% by weight sulfuric acid at 25°C ) from 2.0 to 5.0, particularly preferably from 2.5 to 4.0.

Furthermore, the thermoplastic molding composition may comprise one or more graft copolymers, e.g. eg ASA graft copolymers, which are not prepared according to the process of the invention, in which, for example, the concentration by volume of surfactant S2 is not within the claimed range. Typically, the thermoplastic molding composition may comprise such other ASA graft copolymers in an amount of 5 to 50 wt%, preferably 10 to 30 wt%, more preferably 10 to 20 wt%, based on the composition. full molding.

Additional K additive

The thermoplastic molding composition may optionally comprise 0 to 40 wt%, preferably 0 to 10 wt%, also preferably 0.01 to 40 wt%, more preferably 0.01 to 10 wt%, also preferably from 0.1 to 5% by weight, based on the total molding composition, of at least one additional additive K.

The optional additional component K can be selected from among the commonly known additives and/or auxiliary agents for plastic materials. With regard to conventional auxiliaries and additives, reference is made by way of example to "Plastics Additives Handbook", Ed. Gachter and Müller, 4th edition, Hanser Publ., Munich, 1996. For example, the at least one additional component K can be selected from fillers, reinforcing agents, colorants, pigments, lubricants or mold release agents, stabilizers, in particular light and heat stabilizers, antioxidants, UV absorbers (such as HALS stabilizers), plasticizers, impact agents, antistatic agents (eg, block copolymers prepared from ethylene oxide-propylene oxide, eg, Pluronic® products from BASF SE), flame retardants, bactericides, fungicides, optical brighteners, and blowing agents .

The at least one other optional component K is preferably selected from dyes, pigments, lubricants or mold release agents, stabilizers, in particular light stabilizers, antistatic agents, flame retardants and fillers, in particular mineral fillers. In a preferred embodiment, the thermoplastic composition comprises from 0.01 to 10% by weight, also preferably from 0.1 to 5% by weight, based on the total molding composition, of at least one other additive K selected from dyes, pigments , lubricants or mold release agents, stabilizers, antistatic agents, flame retardants and fillers.

Furthermore, the thermoplastic composition may comprise as additional component K residues of the surfactant S, initiators, buffers, etc. used for the production of graft copolymer B as described below.

In particular, the thermoplastic molding composition may optionally comprise 0 to 10% by weight, preferably 0.1 to 10% by weight, of pigments and/or colorants. Pigments and colorants for graft copolymer rubber compositions, in particular ASA compositions, are commonly known, for example, the pigment and/or colorants may be selected from titanium dioxide, phthalocyanines, ultramarine blue, iron oxides or black. smoke, and also all kinds of organic pigments.

In particular, the thermoplastic molding composition may optionally comprise 0 to 3.5% by weight, preferably 0.01 to 3.5% by weight of typical stabilizers, in particular UV stabilizers. Common stabilizers for thermoplastic polymers include stabilizers to improve thermal stability, which are commonly agents to counteract thermal decomposition, light stabilizers (stabilizers to increase resistance to light), and stabilizers to increase resistance to hydrolysis and chemicals. . Examples of suitable light stabilizers are various substituted resorcinols, salicylates, benzotriazoles and benzophenones. Examples of suitable stabilizers are hindered phenols, but also vitamin E and compounds whose structure is analogous to them. Also suitable is the use of HALS stabilizers (Hindered Amine Light Stabilizers), benzophenones, resorcinols, salicylates and benzotriazoles.

Mentionable examples of fillers, which may be selected from particulate fillers or reinforcing agents, are silicates, amorphous silica, calcium silicates, such as wollastonite, quartz powder, mica, metal oxides, metal hydroxides, carbon black , graphite, barium sulfate, calcium carbonate, magnesium carbonate, bentonites, talc, kaolin, carbon fibers or glass fibers in the form of glass cloth, glass mats or glass silk rovings, crushed glass or glass beads glass. In particular, at least one particulate filler (preferably at least one mineral filler) can be used as additional component K.

Examples of suitable antistatic agents are amine derivatives, such as N,N-bis(hydroxyalkyl)alkylamines or -alkyleneamines, alkylsulfonates, polyethylene glycol esters, copolymers composed of ethylene glycol oxide and propylene oxide, glycol, and mono- and distearates. of glycerol, and also mixtures of these.

Suitable lubricants or mold release agents are fatty acids having from 12 to 30 carbon atoms, salts and derivatives thereof, for example, stearic acid and stearates, stearyl alcohol, stearic esters, amide waxes (eg, stearamides). , in particular ethylene bis(stearamide) (EBS)) and polyolefin waxes. Particularly suitable lubricants and mold release agents are stearic acid, stearates (eg, magnesium stearate), ethylene bis(stearamide) (eg, Irgawax®, Ciba, Switzerland), and mixtures thereof. Preferably, the thermoplastic molding composition comprises from 0.05 to 5% by weight, preferably from 0.1 to 3% by weight, based on the total thermoplastic molding composition, of at least one lubricant or mold release agents, more preferably ethylene bis(stearamide) and/or magnesium stearate.

In particular, the thermoplastic molding composition may optionally comprise 0 to 2% by weight, preferably 0.01 to 2% by weight, of at least one common processing aid, e.g. eg selected from lubricating and mold release agents and antistatic agents.

Steps a) and b) of emulsion polymerization

The graft copolymer latex B is prepared in steps a) and b) according to the invention by emulsion polymerization. Typical embodiments of emulsion polymerization, in batch or continuous mode, are well known to those skilled in the art.

The process of the invention comprises the preparation of at least one grafting base B1 by emulsion polymerization of optional monomers B11, B12 and B13, preferably monomers B11 and B12, where at least one surfactant S1 is added (step to). Preferred embodiments of the monomers B11, B12 and B13, as well as of the grafting base B1 are described above.

Before and/or during the emulsion polymerization in step a) additives can be added as described below, such as surfactants, pH buffers, initiators and molecular weight regulators. Preferably, the at least one surfactant S1 is selected from one or more surfactants S as described below.

Typically, the at least one surfactant S1 is added in step a) in an amount of 0.1 to 5% by weight, preferably 0.2 to 3% by weight, particularly preferably 0.4 to 2%. by weight, based on the total amount of monomers B11, B12 and B13 used in the preparation of the graft base B1 (step a).

Typically, the emulsion polymerization of the at least one graft base B1 (step a) is carried out at a temperature in the range of 20 to 90°C, preferably 30 to 80°C, more preferably 50 to 70 °C Typically, the monomers B11, B12 and optionally B13 are added all at once, continuously or stepwise to the aqueous reaction medium, which preferably contains at least one surfactant S1 and at least one initiator and optionally a buffer. Preferably, the total amount of monomer B11, B12 and/or optionally B13 is added continuously or stepwise within a period of 10 min to 4 h, preferably 1 to 3 h. Preferably, the emulsion polymerization in step a) is then continued for a period of 10 to 120 min, preferably 30 to 100 min.

Typically, the solids content of the graft base latex B1 obtained in step a) is in the range of 15 to 40% by weight, preferably 35 to 45% by weight. Typically, the solids content (eg, of the graft base latex B1 or the graft copolymer latex B) refers to and is equal to the content by weight of non-volatile compounds in the composition (eg, ., in the graft base latex B1 or in the graft copolymer latex B). The solids content is in particular equal to the solids content determined gravimetrically by removing the volatile compounds (particularly water), for example by evaporation at 150 to 180°C for about 10 to 120 min in a drying oven.

Preferably, the mean particle diameter Dw of the graft base latex B1 obtained in step a) is in the range from 50 to 800 nm, preferably from 60 to 600 nm, more preferably from 60 to 200 nm, particularly preferably from 60 to 150 nm, also preferably from 200 to 800 nm, more preferably from 300 to 500 nm. It is also possible to use a graft base B1 having a mean particle diameter Dw in the range 50 to 200 nm, preferably 60 to 100 nm, obtained as described above as a seed latex and polymerize the monomers B11 and B12 additions in the presence of said seed latex. In this embodiment, the graft base B1 obtained in step a) preferably has a mean particle diameter Dw in the range of 200 to 800 nm, preferably 300 to 600 nm, more preferably 350 to 550 nm.

The process of the invention comprises the preparation of at least one graft copolymer B by emulsion polymerization of at least one optional monomer B21 and B22 in the presence of at least one graft base B1, where at least one surfactant S2 is added (step b). Preferred embodiments of monomers B21 and B22, as well as graft copolymer B, are described above.

According to the process of the invention, the graft copolymer B is obtained in step b) in the form of a latex with a mean particle diameter Dw in the range of 60 to 800 nm, preferably 60 to 600 nm, more preferably 60 to 200nm, particularly preferably 70 to 180nm, also preferably 300 to 800nm.

The particle size of the latex particles can be governed during the synthesis by suitable means known in the literature, e.g. eg document DE-A 2826925.

Typically, the particle size distribution, the weight mean particle diameter Dw and the median particle size D50 value can be determined using an ultracentrifuge (eg, as described by W. Scholtan, H. Lange: in Kolloid Z. u. Z. Polymere 250, pp 782-796 (1972)) or a disk centrifuge (eg, DC 24000 from CPS Instruments Inc.). The median particle diameter D50 represents the value of the particle size distribution curve where 50 vol. of the particles (eg, polyacrylate latex particles) have a diameter less than the D50 value and the other 50 vol. have a diameter greater than the D50 value. Similarly, for example, the D90 values give the particle diameter, where 90 vol. of all particles have a smaller diameter.

The weight average particle diameter Dw (or Broucker average particle diameter), also called the average particle diameter Dw, is an average size based on the unit weight of the particle. For example, the weighted mean particle size diameter Dw can be given as:

Dw = sum (ni * Di4) / sum (ni * Di3)

where ni: number of particles of diameter Di

(e.g. G. Lagaly, O. Schulz, R. Ziemehl: Dispersion und Emulsionen: Eine Einführung in die Kolloidik feinverteilter Stoffe einschlielilich der Tonminerale, Darmstadt: Steinkopf-Verlag 1997, ISBN 3-7985-1087-3, page 282 , formula 8.3b). The summation is normally done from the smallest to the largest diameter of the size distribution. of the particles. It should be noted that, for a particle size distribution of particles with the same density, the volume average particle size diameter is equal to the weighted average particle size diameter.

Preferably, the weight average particle diameter Dw can be determined by measuring turbidity as described by Lange, in Kolloid-Zeitschrift und Zeitschrift für Polymere, volume 223, number 1.

According to the process of the invention, the volume concentration of the total amount of surfactant S2 (used in all stages b) of graft emulsion polymerization) is in the range of 0.5 to 0.75 mol/m3, preferably 0.5 to 0.7 mol/m3, more preferably 0.55 to 0.65 mol/m3, based on the volume of the graft copolymer latex particles B.

In the case of two or more graft covers, e.g. eg two-stage graft copolymer B, including graft B2' and B2", the volume concentration of the sum of the surfactant S2 added in all the graft emulsion polymerization stages is within the range of 0.5 to 0.75 moles/m3, preferably 0.5 to 0.7 moles/m3, more preferably 0.55 to 0.65 moles/m3, based on the volume of the graft copolymer latex particles B.

Typically, the volume concentration O in moles/m3 (referred to as O (theta) below) of the surfactant S2 can be calculated according to the following formula:

^1_ w ( S2)-p ( B)-\06

3{theta)

6 ^'M (S2)

where

O (theta) is the volume concentration of surfactant S2, expressed in moles/m3;

w(S2) is the mass fraction of surfactant S2 in grafting step b) relative to the solids content of graft copolymer B (i.e. w(S2)=m(S2)/m(B)),

M(S2) is the molar mass of the surfactant S2, expressed in g/mol,

p(B) is the density of graft copolymer B, expressed in g/cm3.

Preferably, the addition of surfactant S2 in step b) can be carried out

- before or parallel to the addition of monomers B11 and B12;

- after the addition of monomers B11 and B12; me

- after graft emulsion polymerization is complete, but before precipitation (step c)) of the graft copolymer latex.

In a preferred embodiment, the at least one surfactant S2 is added before the emulsion polymerization in step b) (graft emulsion polymerization), that is, before the addition of the monomers B21 and B22, in an amount such that the volume concentration of the total amount of surfactant S2 is in the range of 0.5 to 0.75 mol/m3, based on the volume of the graft copolymer latex particles B obtained in step b).

In a preferred embodiment, the at least one surfactant S2 is added after the emulsion polymerization of the graft shell B2 (i.e. after the graft emulsion polymerization) in step b), wherein the graft copolymer B comprises (preferably consists of):

B1: 50 to 90% by weight, preferably 55 to 90% by weight, more preferably 55 to 65% by weight, based on graft copolymer B, of at least one graft base B1 as described above, and B2: 10 to 50% by weight, also preferably 10 to 45% by weight, more preferably 35 to 45% by weight, based on the graft copolymer B, exactly from a graft shell B2, which is obtained by emulsion polymerization in the presence of at least one graft base B1 of:

B21: 70 to 80% by weight, based on graft cover B2, of at least one vinylaromatic monomer B21, wherein monomer B21 is selected from styrene, a(alpha)-methylstyrene, and mixtures of styrene and one additional monomer selected from a(alpha)-methylstyrene, p-methylstyrene, Ci-C4 alkyl (meth)acrylate (eg, methyl (meth)acrylate, ethyl (meth)acrylate), preferably selected from styrene, a( alpha)-methylstyrene or mixtures of styrene and (alpha)-methylstyrene or methyl (meth)acrylate, and

B22: 20 to 30% by weight, based on graft cover B2, of at least one ethylenically monomer unsaturated B22, wherein monomer B22 is selected from acrylonitrile or mixtures of acrylonitrile and at least one additional monomer selected from methacrylonitrile, acrylamide, vinyl methyl ether, unsaturated carboxylic acid anhydrides (eg, maleic acid anhydride, phthalic acid anhydride ) and imides of unsaturated carboxylic acids (eg, N-substituted maleimide, such as N-cyclohexylmaleimide and N-phenylmaleimide), preferably selected from acrylonitrile or mixtures of acrylonitrile and methacrylonitrile; wherein the total sum of the graft base(s) B1 and the graft cover(s) B2 is 100% by weight,

and wherein the graft copolymer B is obtained in step b) in the form of a latex having an average particle diameter Dw in the range of 60 to 200 nm.

In a particular preferred embodiment

the surfactant S2 or the surfactants S2 and S1 are selected from arylalkylsulfonates and alkylsulfonates having a linear or branched aliphatic hydrocarbon chain of from 5 to 30, preferably from 8 to 30, preferably from 10 to 18, carbon atoms, in particular their salts of sodium or potassium

the precipitation solution comprises at least one magnesium salt, preferably magnesium sulfate, and the concentration of the surfactant S2 is selected such that the weight ratio of sulfur (S) to magnesium (Mg), denoted w(S) : w (Mg), in the thermoplastic molding composition obtained in the process of the invention, is below 2.6, preferably in the range of 1 to 2.5, more preferably in the range of 1.5 to 2.5 . Typically, the emulsion polymerization of the at least one graft copolymer B (step b) is carried out at a temperature in the range of 20 to 90°C, preferably 30 to 80°C, more preferably 50 to 70°C. c. Typically, monomer B21 and optionally B22 are added all at once, continuously or stepwise to the aqueous reaction medium, which contains at least one grafting base B1 and preferably at least one surfactant S2 and at least one initiator and optionally a buffer. . Preferably, the total amount of monomer B21 and optionally B22 and/or B13 is added continuously or stepwise within a period of 10 minutes to 4 hours, preferably 1 to 3 hours. Preferably, the emulsion polymerization in step b) continues after the addition of monomers for a period of 10 to 120 min, preferably 30 to 100 min.

Typically, the solids content of the graft copolymer latex B obtained in step b) is in the range of 15 to 40% by weight, preferably 35 to 45% by weight. Typically, the solids content is determined as described above.

Typically, the graft emulsion polymerization for preparing the at least one graft shell B2 (eg, B2' and B2") (step b)) is conveniently carried out in the same vessel as the emulsion polymerization for prepare the at least one graft base B1 (step a)).

Before and/or during the emulsion polymerization steps a) and b), additives can be added, such as surfactants S1 and S2, pH buffers and initiators.

Suitable surfactants, buffers and initiators are described in WO 2015/150223 and WO 2015/078751.

Furthermore, a molecular weight regulator can be used for the preparation of the at least one graft base B1 and/or for the preparation of the at least one graft copolymer B. Preferably, a molecular weight regulator is used in an amount of 0.01 to 2% by weight, more preferably 0.05 to 1% by weight, based on the total amount of monomers used for the emulsion polymerization. Examples of suitable molecular weight regulators are alkyl mercaptans, such as n-dodecyl mercaptan, t-dodecyl mercaptan; dimeric a(alpha)-methylstyrene and terpinolenes.

Suitable initiators for producing the graft base B1 and/or for the emulsion polymerization of at least one graft copolymer B are arbitrary initiators commonly known to those skilled in the art. Preferably, at least one organic and/or inorganic peroxide compound (comprising at least one R-O-O-H and/or R-O-O-R peroxide group) is used as initiator. Inorganic peroxide salts, such as aluminum, sodium or potassium persulfate, perphosphate or perborate, can be used in particular. Most preferred are sodium and potassium persulfates.

In a preferred embodiment of the invention, an inorganic peroxide salt, preferably an inorganic persulfate salt, preferably sodium persulfate and/or potassium persulfate, is used as initiator for the emulsion polymerization of graft copolymer B.

Typically, the at least one initiator is added during the emulsion polymerization in step a) and/or b) in an amount of 0.01 to 1% by weight, preferably 0.05 to 0.5% by weight, more preferably 0.1 to 0.2% by weight, based on the total amount of monomers used in the respective emulsion polymerization step (step a) and/or b)).

In a preferred embodiment, the preparation of the graft base B1 by emulsion polymerization in step a) and/or the preparation of the graft copolymer B by emulsion polymerization in step b) is carried out by adding at least one persulfate as initiator, wherein the initiator is added in step a) and/or b) in an amount of 0.01 to 1% by weight, preferably 0.05 to 0.5% by weight, more preferably of 0.1 to 0.35% by weight, based on the total amount of monomers used in the respective emulsion polymerization step.

A suitable buffer is typically used to produce graft copolymer B, e.g. eg sodium carbonate or sodium bicarbonate.

In a preferred embodiment, the monomers, especially the monomers B21 and B22 of the at least one graft shell B2, can be added to the reaction mixture all at once or continuously or staggered in several stages, preferably continuously, during polymerization. When monomers B21 and/or B22 are added in several stages (wherein the stages differ in monomer selection, monomer amounts and/or monomer ratio) a multi-layer graft cover B2 is typically obtained. Especially for the preparation of the at least one graft cover B2, the monomers B21 and B22 are added separately or in the form of a monomer mixture continuously to the at least one graft base B1, in the appropriate amounts and proportions. . Typically, the monomers in both steps a) and b) are added in a manner known to one of skill in the art.

Generally, the temperature during the emulsion polymerization of the graft copolymer B (steps a) and b)) is from 25 to 160°C, preferably from 40 to 90°C. Typically, temperature management can be applied during the reaction, such as an isothermal process. Preferably, the polymerization is carried out so that the temperature difference between the start and the end of the reaction is less than 20°C, preferably less than 15°C and more preferably less than 5°C.

Preferably, the at least one graft copolymer latex B obtained after step b) comprises less than 0.1% by weight, preferably less than 0.08% by weight, based on the total solids content of the graft copolymer B, coagulated latex particles (clot).

Surfactant S

In terms of the present invention, a surfactant is a compound that lowers the surface tension of the aqueous phase. Generally, a surfactant and/or a protective colloid help to stabilize a dispersion, in particular a suspension, emulsion or suspoemulsion against settling. The surfactants used as surfactants S (in particular S1 and S2) are preferably compounds, which have molecular weights below 5,000 g/mol, preferably below 2,000 g/mol. They can be anionic, cationic or non-ionic in nature. Preferably, ionic compounds, more preferably anionic compounds, commonly known as surfactants such as surfactant S, are used.

The at least one surfactant S, in particular the surfactant S1 and/or S2, is preferably used in an amount of 0.1 to 5% by weight, preferably 0.2 to 3% by weight, particularly preferably 0. 0.4 to 2% by weight, based on the total amount of monomers used in the respective emulsion polymerization step (step a) or step b)).

Typically, the surfactant S1 and S2 may be selected independently of each other, preferably from the surfactants described below. More preferably, the surfactants S1 and S2 added in step a) and b) are the same surfactant.

In a preferred embodiment, the surfactant S1 used for the emulsion polymerization of the at least one graft base B1 and/or the surfactant S2 used for the graft emulsion polymerization of the at least one graft copolymer B are selected from anionic surfactants . Preferably, the surfactants S1 and/or S2 are selected from alkylsulfonic acids, arylalkylsulfonic acids, alkylsulfates, alkylsulfonates, arylalkylsulfonates, fatty acids, soaps of saturated or unsaturated fatty acids, as well as disproportionate or hydrated alkaline abietic acid or tallow oil acids or mixtures of them. Surfactants S1 and/or S2 comprising carboxylic groups are preferably used, e.g. eg salts of C10-C18 fatty acids, disproportionate abietic acid or tallow oil acids, surfactants according to DE-OS 3639904 and DE-OS 3913509.

Examples of suitable surfactants S1 and S2 are ethoxylated mono-, di- and trialkylphenols having 4 to 9 carbon atoms in the alkyl radical and a degree of ethoxylation (EO number) of 3 to 50, ethoxylated fatty alcohols having 8 up to 36 carbon atoms in the alkyl radical and an EO number from 3 to 50, fatty alcohol sulfonates, sulfosuccinates, ether sulfonates, resin soaps, and also the alkali metal or ammonium salts of alkyl sulfonates having from 8 to 12 atoms carbon atoms in the alkyl radical and salts of higher fatty acids having from 10 to 30 carbon atoms in the alkyl radical. Other suitable surfactants are found in Houben-Weyl, Methoden der organischen Chemie, vol. XIV/1, Makromolekulare Stoffe, Georg-Thieme-Verlag, Stuttgart, 1961, p. 192-206.

Other suitable anionic surfactants S are bis(phenylsulfonic acid) ethers and their alkali metal salts or ammonium, where these carry a C4-C24 alkyl group on one or both aromatic rings. These compounds are described, for example, in US 4,269,749.

In a preferred embodiment, the at least one surfactant S1 and/or S2 is one or more anionic surfactants, selected from alkylsulfonic acids, arylalkylsulfonic acids (in particular alkylbenzenesulfonic acids, such as dodecylbenzenesulfonic acid), fatty acids and salts thereof, preferably their sodium or potassium salts, having a linear or branched aliphatic hydrocarbon chain of 5 to 30, preferably 8 to 30, preferably 10 to 18 carbon atoms. Preferably, the at least one surfactant S1 and/or S2 is one or more compounds selected from sodium or potassium salts of arylalkylsulfonates, alkylsulfonates and fatty acids having from 10 to 18 carbon atoms.

The at least one surfactant S1 and/or S2 can be selected from fatty acids, in particular fatty acids having an aliphatic hydrocarbon chain of 10 to 30, preferably 10 to 18, carbon atoms and their sodium and potassium salts. More preferably, the surfactant C is at least one fatty acid selected from oleic acid, stearic acid, palmitic acid and their sodium and potassium salts.

In a preferred embodiment, the at least one surfactant S1 and/or S2 is selected from alkylsulfonic acids RS(=O)2-OH and salts thereof, preferably sodium and potassium salts, in particular it is selected from alkylsulfonic acids and salts thereof having a linear or branched aliphatic hydrocarbon chain R of 5 to 30, preferably 8 to 30, preferably 10 to 18 carbon atoms. For example, the at least one surfactant S1 and/or S2 can be selected from paraffin sulfonic acid and dodecyl sulfonic acid.

In a preferred embodiment, the surfactant S2 or the surfactants S2 and S1 are selected from arylalkylsulfonates and alkylsulfonates having a linear or branched aliphatic hydrocarbon chain of 5 to 30, preferably 8 to 30, preferably 10 to 18, carbon atoms, in particular sodium or potassium salts thereof.

In another preferred embodiment, the at least one surfactant S1 and/or S2 or the active form of the surfactant S1 and/or S2 are prepared in situ from an alkylsulfonate, arylalkylsulfonate or a fatty acid with an alkali metal hydroxide by conversion to the corresponding salt, which is active as a surfactant in the dispersion. Instead of alkali metal hydroxides, it is also possible to use alkali metal carbonates or alkali metal hydrogen carbonates. Preferably, the at least one surfactant S is at least one fatty acid, preferably selected from oleic acid, stearic acid and palmitic acid, which is converted into the corresponding sodium or potassium salt.

Precipitation stage c)

The process of the invention to produce a thermoplastic molding composition comprises step c) of precipitation of graft copolymer B by mixing the latex of graft copolymer B obtained in step b) with a precipitation solution comprising at least one salt and /or acid. Typically, the graft copolymer latex B obtained in step c) is precipitated using a precipitation solution comprising at least one salt or at least one salt and at least one acid. Preferred salts are selected from magnesium sulfate, calcium chloride; magnesium sulfate monohydrate (kieserite Mg[SO4] • H2O), magnesium sulfate pentahydrate (pentahydrate Mg[SO4] • 5H2O), magnesium sulfate hexahydrate (hexahydrite Mg[SO4] • 6H2O) and magnesium sulfate heptahydrate (epsomite, Mg [SO4] • 7H2O). Preferred acids are selected from sulfuric acid, phosphoric acid and acetic acid.

In a particularly preferred embodiment, the precipitation solution comprises at least one magnesium salt, preferably magnesium sulfate. For example, the precipitation solution can be prepared using anhydrous magnesium sulfate, magnesium sulfate monohydrate (kieserite Mg[SO4] • H2O), magnesium sulfate pentahydrate (pentahydrate Mg[SO4] • 5H2O), magnesium sulfate hexahydrate (hexahydrite Mg[SO4] • 6H2O). Typically, the precipitation solution used in the process of the invention is prepared by mixing water with at least one salt or a saturated solution of the salt and/or at least one acid. Typically, the precipitation solution comprises 0.1 to 5% by weight, preferably 0.2 to 1% by weight of the at least one salt and/or at least one acid.

For example, first, the precipitation solution, e.g. eg in a precipitation tank, then, graft copolymer B is added to the precipitation solution with stirring, and after that, optionally, the obtained precipitation mixture is heated. Typically, the precipitation in step c) is carried out at temperatures in the range of 40°C to 150°C, preferably 60 to 95°C.

Preferably, the total solids content of the graft copolymer latex B used in step c) is in the range of 5 to 45% by weight, preferably 10 to 40% by weight, more preferably 15 to 40% by weight. . In particular, details of a suitable precipitation step in the process of the invention are described, for example, in WO 2017/211783 or WO 2018/060111 (pages 24-25 and 38-39). Dehydration stage d)

The process of the invention for producing a thermoplastic molding composition encompasses step d), wherein the precipitated graft copolymer B obtained in step c) is mechanically dehydrated, optionally washed and/or optionally dried.

Typically, the precipitated graft copolymer B is at least partially dehydrated, in particular by centrifugation and/or filtration. Preferably, the precipitated graft copolymer B is at least partially mechanically dehydrated and separated from the aqueous phase using a centrifuge.

Typically, the graft copolymer B obtained after mechanical dehydration in step d) has a residual moisture level in the range of 10 to 50% by weight, preferably 20 to 40% by weight, more preferably 25 to 35%. % by weight, based on graft copolymer B.

Residual moisture level refers to the amount of water provided in % by weight, based on total wet graft copolymer B. Typically, the residual moisture level can be determined using a suitable apparatus, such as a drying scale. Typically, the sample is dried for a set period as long as a constant weight level is maintained. For example, the residual moisture level can be determined on the Mettler-Toledo Halogen Moisture Analyzer HR73, at 180°C, holding a constant weight for 30 seconds.

In a further preferred embodiment, graft copolymer B is washed one or more times after mechanical dehydration wherein the separated graft copolymer B is contacted with water or a mixture of water and a polar organic solvent miscible with water ( optional wash step). After washing, graft copolymer B is typically separated from water, e.g. eg by centrifugation.

Optionally, the dehydrated or dehydrated and washed graft copolymer B may be dried, for example, using a cabinet dryer or other common known drying apparatus, such as a flash dryer or fluidized bed dryer. Graft copolymer B can also be dried as described in DE-A 19907136. Typically, the optional drying step is carried out at a temperature in the range of 50 to 160°C.

Preferably, the graft copolymer B obtained in step d) is in the form of a dry polymer latex powder having a residual moisture level of less than 5 wt%, preferably less than 2 wt%, more preferably less 1% by weight thereafter.

It is also suitable to mix the graft copolymer B in step e) in the form of a wet crumb (without dyeing step) with a residual moisture level of 1 to 40% by weight, in particular 20 to 40% by weight, after whereof the complete drying of the graft copolymers takes place during the mixing process (step e). For example, graft copolymer B can be dried as described in EP-A 0735 077, wherein the precipitated and dehydrated graft copolymer B is directly extruded including the addition of component A and optionally components C and/or K and wherein the residual water of the dehydrated graft copolymer is completely removed as a vapor or partially as a vapor and partially as a liquid. Mixing stage e)

The process of the invention for producing a thermoplastic molding composition comprises step e), wherein the graft copolymer B (in particular the dry graft copolymer powder) obtained in step d) is mixed with the at least one copolymer thermoplastic A and optionally with additional components C and/or K, where the mixture can be carried out successively or simultaneously.

Methods and devices for mixing graft copolymer B with other polymers and/or other components selected from the additives and auxiliary agents mentioned above are known to those skilled in the art. Typically, step e) comprises melt mixing and/or melt extrusion and may be carried out using one or more kneaders, extruders and/or twin-shaft screws.

Preferably, the mixing in step e), in particular the mixing of dry graft copolymer B, thermoplastic copolymer A and optional additional components K, is carried out at temperatures in the range of 200 to 300°C.

In particular, details of the suitable mixing step in the process of the invention are described in WO 2017/211783 or WO 2018/060111 (pages 31 and 41).

In a preferred embodiment, the thermoplastic molding composition obtained by the process of the invenci A or A n p 1 sents A or A na resistivity sup 1erficial esp 1ecífica determined sec ^ 1 A C A A 1 IE 62631-3-2: 2015 , in the range of 6.4*10 to 9.14*10 Ohm, preferably in the range of 7*10 to 9*10 Ohm, more preferably in the range of 7.5*1014 to 8.5*1014 Ohm .

The thermoplastic compositions of the invention can be used to produce formed parts by any commonly known method, e.g. g., injection molding, extrusion, blow molding. For example, the formed parts can be selected from plates, semi-finished products, films, fibers and foams. In particular, said molded parts can be used, for example, in the automotive sector, e.g. eg in the construction of bodywork for vehicles, for the interior of automobiles. The molded materials of the invention can be used, in particular, in the construction of ships, aircraft or trains, in particular as trim parts, inner fender components, dashboards, seat shell construction, bulkheads. Furthermore, non-automotive applications of the molded materials of the invention are also conceivable, e.g. eg formwork plates, cladding elements, support shells and roof components.

The present invention is further illustrated by the following examples and claims.

experimental examples

1. Preparation of graft copolymer B

The basic poly(butyl acrylate) latex (graft base B1) used in the following examples 1.1 to 1.3 was produced using the same recipe (see example 1.1) with a particle diameter Dw of about 75 nm. A mixture of primary and secondary sodium (C12-C18) alkylsulfonates with an average chain length of C15 and an average molecular weight M = 288.84 g/mol is used as surfactant S1 (graft base preparation B1) and as S2 surfactant (grafting step). The volume concentration (determined according to example 3.3) of the added surfactant S2 during the grafting step, ie the emulsion polymerization of monomers B21 and B22, was varied. The amount of coagulum in the graft copolymer B latexes was determined as described in example 3.2. The amounts and results are summarized in Table 1.

1.1 Component B-1

In a first stage, a basic poly(butyl acrylate) latex (graft base B1) was prepared as described below:

The reaction vessel was charged with 86.12 pbw of demineralized water, 0.61 pbw of surfactant S1 (C12-C18 paraffin sulfonic acid sodium salt, M=288.84 g/mol) and 0. 23 parts by weight of sodium bicarbonate. When the temperature in the reaction vessel reached 59°C, 0.18 parts by weight of potassium persulfate, dissolved in 5 parts by weight of demineralized water, were added. A mixture of 59.51 pbw of butyl acrylate (monomer B11) and 1.21 pbw of tricyclodecenyl acrylate (dihydrodicyclopentadienyl acrylate, DCPA) (monomer B12) was added over a period of 210 min. Subsequently, the reaction continued for 60 min. Finally, the polymer dispersion had a total solids content of 39.6% and the latex particles had an average particle diameter Dw of 75nm. The particle size was determined by turbidity as described in example 3.1.

Subsequently, graft cover B2 was obtained by emulsion polymerization of styrene and acrylonitrile in the presence of the basic poly(butyl acrylate) rubber latex (graft base B1). An amount of 152.87 parts by weight of the basic latex described above was added to the reaction vessel together with 90.37 parts by weight of demineralized water, 0.11 part by weight of surfactant S2 (C12 paraffin sulfonic acid sodium salt -C18) and 0.16 parts by weight of potassium persulfate, dissolved in 5.22 parts by weight of demineralized water. In a period of 190 min, a mixture of 77% by weight of styrene and 23% by weight of acrylonitrile was added, where in a first stage 6.49 parts of styrene and 1.94 parts of acrylonitrile are added in 20 min, followed by 20 min hold time, after which 24.69 parts of styrene and 7.37 parts of acrylonitrile are added in 150 min. The monomer addition takes place at a temperature of 61°C, followed by a post-polymerization time of 60 min at 65°C. A polymeric dispersion (component B-1) with a total solids content of 39.5% was obtained. The latex particles had a mean particle diameter Dw of 87 nm (determined by turbidity). The coagulum, as described in Example 3.2, was determined to represent 0.058% by weight, based on the total solids content of the graft copolymer B latex.

1.2 Component B-2 (comparative example)

An amount of 152.87 parts by weight of the basic poly(butyl acrylate) rubber latex (graft base B1) as described in example 1.1 was added to the reaction vessel together with 90.37 parts by weight of water. demineralized, 0.08 parts by weight of the surfactant S2 and 0.16 parts by weight of potassium persulfate, dissolved in 5.22 parts by weight of demineralized water.

In a period of 190 min, a mixture of 77% by weight of styrene and 23% by weight of acrylonitrile was added, where in a first stage 6.49 parts of styrene and 1.94 parts of acrylonitrile are added in 20 min, followed by 20 min hold time, after that 24.69 parts of styrene and 7.37 parts of acrylonitrile are added in 150 min. The monomer addition takes place at a temperature of 61°C, followed by a post-polymerization time of 60 min at 65°C. A polymeric dispersion (component B-2) with a total solids content of 39.5% by weight is obtained. The latex particles had a mean particle diameter Dw of 91 nm determined by turbidity as described in example 3.1. As described in Example 3.2, it was determined that the coagulum represented 0.128% by weight, based on the total solids content of the graft copolymer latex B.

1.3 Component B-3 (comparative example)

An amount of 152.87 parts by weight of the basic poly(butyl acrylate) rubber latex (graft base B1) as described in example 1.1 was added to the reaction vessel together with 90.37 parts by weight of water. demineralized, 0.12 parts by weight of the C12-C18 paraffin sulfonic acid sodium salt (M=288.84 g/mol) and 0.16 parts by weight of potassium persulfate, dissolved in 5.22 parts by weight of demineralized water.

In a period of 190 min, a mixture of 77% by weight of styrene and 23% by weight of acrylonitrile was added, where in a first stage 6.49 parts of styrene and 1.94 parts of acrylonitrile are added in 20 min, followed by 20 min hold time, after that 24.69 parts of styrene and 7.37 parts of acrylonitrile are added in 150 min. The monomer addition takes place at a temperature of 61°C, followed by a post-polymerization time of 60 min at 65°C. A polymeric dispersion (component B-3) with a total solids content of 39.5% by weight was obtained. The latex particles had a mean particle diameter Dw of 91 nm determined by turbidity as described in example 3.1. The coagulum, as described in Example 3.2, was determined to represent 0.106% by weight, based on the total solids content of the graft copolymer latex B.

Table 1: ASA Graft Copolymer Latex

Unit Ex.-1.1 (Invention) Ex.-1.2 (Comparative) Ex.-1.3 (Comparative) Graft copolymer B-1 B-2 B-3

Conc. in Volume S2 (O) moles/m3 0.69 0.47 0.76 Coagulum % by weight 0.058 0.128 0.106

Surprisingly, it was found that for a volume concentration of sodium alkyl sulfonate (surfactant S2) of more than 0.43 mol/m3, as well as for volume concentrations lower than 0.69 mol/m3, very low amounts of coagulum are observed. after preparation of graft copolymer latex. About twice the amount of coagulum is found in Comparative Examples Ex-II (relative to B-2) and Ex-III (relative to B-3). The lower amount of coagulum significantly reduces the cleaning effort in the plant.

1.4 Precipitation stage

Each of the graft copolymer latices B obtained in Examples 1.1 to 1.3 was separately coagulated in a magnesium sulfate solution. Each of the graft copolymer B latexes obtained in examples 1.1 to 1.3 was dosed into a stirred tank together with a magnesium sulfate solution (18% by weight) at a temperature of about 88°C. The concentration of magnesium sulfate, based on the total aqueous phase in the tank, was approximately 0.8% by weight and the concentration of the graft copolymers (B-1, B-2 or B-3), calculated as solid and based on the total content of components in the tank was approximately 18% by weight.

Each of the precipitated graft copolymers B-1, B-2 or B-3 was filtered off, washed twice with 21 L of water and dried in a laboratory oven (2 days, 60-70°C). ) thereafter. Graft copolymer components (graft copolymer powder) B-1, B-2 and B-3 with a water content of <1% by weight were obtained.

2. Preparation of thermoplastic molding compositions

2.1 Each of the graft copolymer components B-1, B-2 and B-3 (graft copolymer powders) obtained in Example 1 were mixed with the component

A-1: Luran VLP (styrene-acrylonitrile copolymer with 35% by weight of acrylonitrile and a viscosity number VN of 80 ml/g (determined according to DIN 53726 at 25°C, 0.5% by weight in dimethylformamide),

to obtain a thermoplastic molding composition. A Coperion ZSK 25 extruder was used for the melt blending of components A and B, where the temperature of the dough was in the range of 220 to 250°C. The amounts of components B-1/B-2/B-3 and A-1 are provided in Table 2 below.

2.2 Specimens of thermoplastic molding compositions used for mechanical testing and other testing methods were obtained by injection molding using an Arburg machine under standard conditions, i.e., 250°C to 270°C melt temperature, 70°C tool temperature.

2.3 The compositions and test results (determined according to examples 3.4 to 3.6) are summarized in the following table 2:

Table 2: Thermoplastic molding composition and test result

invención) (comparativo) (comparativo) A-1 % en peso 50 50 50 B-1 % en peso 50 - -B-2 % en peso - 50 -B-3 % en peso - - 50 ak Resistencia al impacto Charpy conEx. 2.1a (From Ex.-2.1 b Ex.-2.1 c

invention) (comparative) (comparative) A-1 wt% 50 50 50 B-1 wt% 50 - -B-2 wt% - 50 -B-3 wt% - - 50 ak Charpy impact strength with

_notches kJ/m2 47.5 38.4 38.7 Surface resistivity specif. Ohm 8.05*1014 9.15*1014 6.39*1014 weight ratio 2.1 2.8 2.6 w (S) / w (Mg)

It was found that the graft rubber copolymer B-1, produced according to the invention and blended into the SAN matrix (component A-1), produces a thermoplastic molding composition showing higher notched Charpy impact strength in comparison with graft rubber copolymers B-2 and B-3 (comparative examples).

In addition to the specific range of volumetric concentration O (theta) of the surfactant S2 (see Table 1), the specific surface resistivity of the thermoplastic molding composition comprising components A and B and the mass ratio of sulfur to magnesium in thermoplastic molding compositions as a characteristic to differentiate the samples, that is, to characterize the result of the optimization of the concentration of surfactant. Accordingly, the thermoplastic molding compositions of the invention exhibit a surface resistivity in the range from 6.4*1014 to 9.14*1014 Ohm and/or a mass ratio of sulfur to magnesium w(S) / w( Mg) below 2.6.

3. Test methods

3.1 The mass median particle diameter Dw of the latex particles was determined by turbidity as described by Lange, in Kolloid-Zeitschrift und Zeitschrift für Polymere, vol. 223, number 1.

3.2 The coagulum content after graft emulsion polymerization was determined as follows: The coagulum was separated by filtration from the latex obtained after grafting the monomers B21 (styrene) and B22 (acrylonitrile) using a metal sieve with a size 0.5 mm mesh and/or collected from the reactor wall, thermometer and stirrer. The obtained coagulum was dried in a laboratory oven at 75°C for 14 to 20 h and weighed.

The coagulum content is indicated in % by weight, based on the total mass of graft copolymer B.

3.3 The concentration in volume O in [moles/m3] (denoted theta) of the surfactant S2, was calculated as follows:

_{3{theta )} ^{1_ w(S2)-p(B)-\06}

6 ^'M (S2)

where

O (theta) is the volume concentration of surfactant S2 in moles/m3

w(S2) is the mass fraction of surfactant S in the grafting stage relative to polymer B (i.e. w(S2)=m(S2)/m(B)),

M(S2) is the molar mass of the surfactant S in [g/mol], which is M=288.84 g/mol of S2 used in the examples;

p(B) is the density of graft copolymer B in [g/cm3], which is p=1.087 g/cm3.

The density of graft copolymer B can be calculated based on the mass fraction w and density p of the corresponding homopolymers, p. eg poly(butyl acrylate) (p(PBAK)=1.087 g/cm3), polyacrylonitrile (p(PAN)=1.184 g/cm3) and polystyrene (p(PS)=1.05 g/cm3). For example, the density p(B) of graft copolymer B can be calculated: p(B)=[w(PBAK) w(PAN) w(PS)] / [[w(PBAK)/p(PBAK)] [w(PAN)/p(PAN)] [w(PS)/p(PS)]] =

[0.6 0.092 0.308]/[[0.6/1.087 g/cm3] [0.092/1.184 g/cm3] [0.308/1.05 g/cm3]] = 1.087 g/cm3.

3.4 Notched Charpy impact strength was measured according to DIN 53453 (ISO 1791eA) using specimens obtained by injection molding according to example 2.2.

3.5 The specific surface resistivity (expressed in ohms) was determined according to IEC 62631-3-2: 2015 using specimens obtained by injection molding according to example 2.2.

3.6 The amounts of the elements sulfur (S) and magnesium (Mg) and the following weight ratio w(S)/w(Mg) were determined using inductively coupled plasma optical emission spectrometry (ICP-OES). The specimens obtained according to example 2.2. were used for ICP-OES.

Claims (15)

1. A process for the preparation of a thermoplastic molding composition comprising: A: 5 to 95% by weight, based on the total molding composition, of at least one thermoplastic copolymer A, comprising at least one vinylaromatic monomer A1 and optionally at least one additional ethylenically unsaturated monomer A2; B: 5 to 70% by weight, based on the total molding composition, of at least one graft copolymer B comprising: B1: 50 to 90% by weight, based on graft copolymer B, of at least one graft base B1 obtained by emulsion polymerization of: B11: 70 to 99.9% by weight, based on the graft base B1, of at least one Ci-C8 alkyl (meth)acrylate as monomer B11; B12: 0.1 to 10% by weight, based on the graft base B1, of at least the polyfunctional crosslinking monomer B12; B13: 0 to 29.9% by weight, based on the graft base B1, of at least one additional monoethylenically unsaturated copolymerizable monomer B13 different from B11 and B12; wherein the sum of B11, B12 and optional B13 is 100% by weight; Y B2: 10 to 50% by weight, based on graft copolymer B, of at least one graft shell B2, which is obtained by emulsion polymerization in the presence of at least one graft base B1 of: B21: of 50 to 100% by weight, based on graft cover B2, of at least one vinylaromatic monomer B21, and B22: 0 to 50% by weight, based on graft shell B2, at least one ethylenically unsaturated monomer B22; wherein the total sum of the graft base B1 and the graft cover B2 is 100% by weight; C: 0 to 90% by weight, based on the total molding composition, of at least one additional polymeric component C; Y K: from 0 to 40% by weight, based on the total molding composition, of at least one additional additive K; where the procedure includes the stages of: a) preparation of the at least one grafting base B1 by emulsion polymerization of the optional monomers B11, B12 and B13, where at least one surfactant S1 is added; b) preparation of the at least one graft copolymer B by emulsion polymerization of the at least one optional monomer B21 and B22 in the presence of the at least one graft base B1, wherein at least one surfactant S2 is added before, during and/or or after emulsion polymerization, wherein the graft copolymer B is obtained in the form of a latex with an average particle diameter Dw in the range of 60 to 800 nm; and wherein the volume concentration of the total amount of surfactant S2 is in the range of 0.5 to 0.75 mol/m3, based on the volume of the graft copolymer latex particles B; c) precipitation of the graft copolymer B by mixing the graft copolymer latex obtained in step b) with a precipitation solution comprising at least one salt and/or acid; d) mechanical dehydration, optional washing and/or optional drying of the precipitated graft copolymer B obtained in step c); e) mixing the precipitated graft copolymer B obtained in step d) with component A and optionally components C and/or K, obtaining the thermoplastic molding composition. 2. The process according to claim 1, wherein the at least one thermoplastic copolymer A comprises A1: from 50 to 99% by weight, based on the copolymer A, of the at least one vinylaromatic monomer A1, selected from styrene, a(alpha )-methylstyrene or mixtures of styrene and at least one additional monomer selected from alpha-methylstyrene, p-methylstyrene and C1-C8 alkyl (meth)acrylate, A2: from 1 to 50% by weight, based on copolymer A, of at least one additional ethylenically unsaturated monomer A2, selected from acrylonitrile or mixtures of acrylonitrile and at least one additional monomer selected from methacrylonitrile, acrylamide, vinyl methyl ether, acid anhydrides unsaturated carboxylic acids and imides of unsaturated carboxylic acids. 3. The process according to claim 1 or 2, wherein the at least one thermoplastic copolymer A comprises: A1: from 65 to 80% by weight, based on the total copolymer A, of the at least one vinylaromatic monomer A1, selected from styrene , a(alpha)-methylstyrene or mixtures of styrene and alpha (alpha)-methylstyrene and A2: from 20 to 35% by weight, based on the total copolymer A, of at least one additional ethylenically unsaturated monomer A2, selected from acrylonitrile or mixtures of acrylonitrile and methacrylonitrile. 4. The process according to any of claims 1 to 3, wherein the at least one graft copolymer B comprises: B1: 55 to 75% by weight, based on graft copolymer B, of at least one graft base B1 obtained by emulsion polymerization of: B11: 90 to 99.9% by weight, based on the basis of graft B1, of at least one C1-C8 alkyl (meth)acrylate, as monomer B11; B12: 0.1 to 10% by weight, based on the graft base B1, of at least the polyfunctional crosslinking monomer B12; wherein monomer B12 is selected from allyl (meth)acrylate, divinylbenzene, diallyl maleate, diallyl fumarate, diallyl phthalate, triallyl cyanurate, triallyl isocyanurate and dihydrodicyclopentadienyl acrylate; B13: 0 to 9.9% by weight, based on the graft base B1, of at least one additional monoethylenically unsaturated copolymerizable monomer B13 different from B11 and B12, wherein monomer B13 is selected from styrene, a(alpha) -methylstyrene, (C1-C4)alkylstyrene, acrylonitrile, methacrylonitrile, isoprene, butadiene, chloroprene, methyl (meth)acrylate, alkylene glycol di(meth)acrylate and vinyl methyl ether, wherein the sum of B11, B12 and optional B13 is 100% by weight, based on all monomers of the graft base B1; Y B2: 25 to 45% by weight, based on graft copolymer B, of at least one graft shell B2, wherein at least one graft shell B2 is obtained by emulsion polymerization in the presence of at least one graft base graft B1 of: B21: 70 to 80% by weight, based on graft cover B2, of at least one vinylaromatic monomer B21, wherein monomer B21 is selected from styrene, a(alpha)-methylstyrene, and mixtures of styrene and one additional monomer selected from a(alpha)-methylstyrene, p-methylstyrene, C1-C4 alkyl (meth)acrylate, and B22: 20 to 30% by weight, based on graft cover B2, of at least one ethylenically unsaturated monomer B22, wherein monomer B22 is selected from acrylonitrile or mixtures of acrylonitrile and at least one additional monomer selected from methacrylonitrile, acrylamide, vinyl methyl ether, unsaturated carboxylic acid anhydrides and unsaturated carboxylic acid imides; wherein the total sum of the graft base(s) B1 and the graft cover(s) B2 is 100% by weight. 5. The process according to any of claims 1 to 4, wherein the graft copolymer B comprises: B1: 50 to 70% by weight, based on the graft copolymer B, of the at least one graft base B1; B2': 10 to 30% by weight, based on graft copolymer B, of at least one graft shell B2', which is obtained by emulsion polymerization, in the presence of graft base B1, of B21': 100% by weight, based on the graft shell B2', of at least one monomer B21', selected from styrene, a(alpha)-methylstyrene or a mixture of styrene and at least one additional monomer selected from a( alpha)-methylstyrene, p-methylstyrene and C1-C4 alkyl (meth)acrylate; Y B2": 20 to 40% by weight, based on graft copolymer B, of at least one graft shell B2", which is obtained by emulsion polymerization, in the presence of graft base B1 grafted with B2', of : B21": from 50 to 95% by weight, based on the graft cover B2", of at least one monomer B21", selected from styrene, a(alpha)-methylstyrene or mixtures of styrene and at least one additional monomer selected from alpha-methylstyrene, p-methylstyrene and C1-C4 alkyl (meth)acrylate, and B22": 5 to 50% by weight, based on the graft cover B2", of at least one monomer B22", selected from acrylonitrile or mixtures of acrylonitrile and at least one additional monomer selected from methacrylonitrile, acrylamide, vinyl methyl ether, anhydrides of unsaturated carboxylic acids and imides of unsaturated carboxylic acids. 6. The process according to any of claims 1 to 5, wherein the graft copolymer B comprises at least two graft copolymers B-I and B-II, wherein: The graft copolymer B-I has a mean particle diameter Dw in the range of 60 to 200 nm, and The graft copolymer B-II has a mean particle diameter Dw in the range of 300 to 800 nm. 7. The process according to any of claims 1 to 6, wherein the at least one vinylaromatic monomer B21 is styrene and/or a(alpha)-methylstyrene and the at least one ethylenically unsaturated monomer B22 is acrylonitrile or a mixture of acrylonitrile and methacrylonitrile . 8. The process according to any of claims 1 to 7, wherein the at least one surfactant S1 and/or S2 are one or more anionic surfactants, selected from alkylsulfonic acids, arylalkylsulfonic acids, fatty acids and salts thereof, having a straight or branched aliphatic hydrocarbon chain of 5 to 30 carbon atoms. 9. The process according to any of claims 1 to 8, wherein the volume concentration of the surfactant S2 in step b) is in the range of 0.5 to 0.7 mol/m3, preferably 0.55 to 0 0.65 mol/m3, based on the volume of the graft copolymer latex particles B. 10. The process according to any of claims 1 to 9, wherein the preparation of the graft base B1 by emulsion polymerization in step a) and/or the preparation of the graft copolymer B by emulsion polymerization in step b ) is carried out by adding at least one persulfate as initiator, wherein the initiator is added in step a) and/or b) in an amount of 0.01 to 1% by weight, based on the total amount of monomers used in the respective emulsion polymerization stage. 11. The process according to any of claims 1 to 10, wherein the thermoplastic molding composition comprises 5 to 60% by weight, based on the total molding composition, of at least one additional polymeric component C selected from polycarbonates, polyamides and polyesters. 12. The process according to any of claims 1 to 11, wherein the thermoplastic molding composition comprises from 0.01 to 10% by weight, based on the total molding composition, of at least one additional additive K, selected from colorants , pigments, lubricants or mold release agents, stabilizers, antistatic agents, flame retardants and fillers. 13. The process according to any of claims 1 to 12, wherein the at least one latex of the graft copolymer B obtained in step b) comprises less than 0.1% by weight, based on the total solids content of the copolymer of graft B, of coagulated latex particles. 14. The method according to any of claims 1 to 13, wherein the thermoplastic molding composition obtained has a specific surface resistivity, determined according to IEC 62631-3-2:2015, in the range of 6.4*1014 to 9, 14*1014 Ohm 15. The method according to any of claims 1 to 14, wherein the surfactant S2 or the surfactants S2 and S1 are selected from arylalkylsulfonates and alkylsulfonates having a linear or branched aliphatic hydrocarbon chain of 5 to 30 carbon atoms, the precipitation solution comprises at least one magnesium salt, and the concentration of the surfactant S2 is selected so that the weight ratio of sulfur (S) to magnesium (Mg) in the obtained thermoplastic molding composition is less than 2.6.